The present invention relates to a self-sounding type of portable anti-theft monitor for use with a shoplifting preventing device, etc.
In a conventional portable anti-theft monitor of this sort, for example, a self-sounding type portable anti-theft monitor (generally called "buzzer tag") which is attached to an article of merchandise, etc. to be monitored for anti-theft purpose by means of wire, etc. mounted to this portable anti-theft monitor, when the article attached with the monitor as it is passes near a gate in an attempt to illegally smuggle it out, the portable anti-theft monitor receives radio waves emitted from a sending antenna at the gate to sound a buzzer incorporated therein giving the alarm.
Further, on receipt of radio waves from the sending antenna, the portable anti-theft monitor emits radio waves with another frequency, which are received by an receiving antenna at the gate to sound also a buzzer disposed at the gate giving the alarm.
In the conventional portable anti-theft monitor, for a releasing mechanism for removing the portable anti-theft monitor from the article, there is adopted a method for mechanically unlocking by inserting a releasing jig through a hole bored in a case in which the wire is locked.
Therefore, since the releasing method for removing the portable anti-theft monitor from the article can be easily judged from outside, the portable anti-theft monitor is illegally removed from the article, and shoplifting cannot be sufficiently prevented.